I still own my two LD players, and all the movies I bought, literally hundreds.
At the time, there wasn't any place to rent LDs, so I ended up purchasing almost anything that I wanted to watch. Of course, a lot of those were from the cut-out bins at Camelot, where you could actually by some movies (not particularly good ones) for less than $15. With their stamp-card program I was able to parlay some of those purchases into discs that I really wanted.
I shudder to think how much money I spent on discs during that time.
Then along came DVDs, and I bought more and more of those, some replacing what I had bought on LD.
Just over a year ago, I decided to try NetFlix, and since then my purchasing has dropped off dramatically.
Six months ago, I bought and HD DVD player, and to date I've only bought two HD DVDs. With the convenience of NetFlix, I only plan on buying HD movies I really, really want. Frankly, I'd rather apply the money I had been spending on content and apply it toward system upgrades.
I don't know if this is a symptom of the changing market, or my own age - I have LDs that have never opened, and may not ever be opened, there's only so much time one can spend watching movies. I do expect that with each change in media format that my actual purchase of physical content will decline.